You can do anything you want if you are willing to pay the consequences. In this case, depending on how much you saw off, you may commit a felony.
Depending on how much you saw off, yes.
A shotgun is a shotgun, regardless of what you do to it (except should its length go below certain limits, it will be reclassified as a pistol or handgun in some jurisdictions). If you saw some of it off, then it becomes a "sawn-off shotgun", pending the above restriction on length.
100 yrs
This is a felony, which is typically a sentence of 12 months or more.
The value of any "Antique" is always a very subjective opinion. research what a similar item has sold for and you will have your answer.
$500
If you have a semi-new shotgun, you can pickup the gun buyers guide from borders or a local book store. If your talking an antique shotgun, then they may have books for that, but I have not looked into it before.
Library, internet, Standard Catalog of Firearms.
See related link.
A Damascus twist steel double barrel shotgun is an antique shotgun made by layering iron and steel and welding them together. This kind of shotgun is worth approximately $3,000 depending on the condition of the weapon.
500 to 1500
You may saw off a shotgun in AR IF you pay the $5 federal tax,federally register it, get fingerprinted, and do the required 6 month wait. After that, you may saw it off.Otherwise:A.C.A. § 5-1-102. Definitions.As used in the Arkansas Criminal Code:........(20) "Sawed-off or short-barreled shotgun" means:(A) A shotgun having one (1) or more barrels less than eighteen inches (18") in length; or(B) Any weapon made from a shotgun, whether by alteration, modification, or otherwise, if the weapon, as modified, has an overall length of less than twenty-six inches (26");